Bash and SSH

.bashrc

Your bash environment is configured via the file ~/.bashrc (or sometimes ~/.bash_profile).

On NAF machines the default is a zsh shell. If you want to change to bash by default, add exec bash to ~/.zprofile

If these files to not exist, you can just create them. It is recommended to make use of shared configurations in artus-analysis/bashrc.

screen

The window manager screen is a very useful tool for multiplexing terminals. Start a screen session with

screen

If a screen screen session already exists, you can reattach it with

screen -r [-d]

Inside a screen session you need the following commands:

Ctrl-a c # create a new window
Ctrl-a n # change to next window
Ctrl-a p # change to previous window
Ctrl-a d # detach session, which continues running in the background

sed

Replace all strings matching search in file file with replace:

sed -i -e "s/search/replace/g" file

The delimiter (here /) can be (almost) freely choosen, but must not be part of search or replace.

Delete lines matching search in file file:

sed -i -e "/search/d" file

SSH Keys

You can generate your own key for SSH authentification using one of the two commands

ssh-keygen -t rsa
ssh-keygen -t dsa

This has to be done only once. Then the public key is then installed on any the remote machine with the corresponding command

ssh-copy-id -i ~/.ssh/id_rsa.pub <user>@<address of remote machine>
ssh-copy-id -i ~/.ssh/id_dsa.pub <user>@<address of remote machine>

in order to simplify the authentification at this machine. A passwort is then only needed to unlock the key.

SSH Config

If not already existing you create a text file in ~/.ssh/config. In this file you can then define settings for connections to remote machines. The Host defines an alias for your SSH connections, such that you can easily connect to a remote machine via ssh naf, for example. Here is a list of settings that is usually needed in our group:

• NAF@DESY

   Host naf
   	Hostname = naf-cms.desy.de
   	Compression = yes
   	User = <user>
   	ForwardX11 = yes
  
   Host naf1
   	Hostname = nafhh-cms01.desy.de
   	Compression = yes
   	User = <user>
   	ForwardX11 = yes
  
   Host naf2
   	Hostname = nafhh-cms02.desy.de
   	Compression = yes
   	User = <user>
   	ForwardX11 = yes
  
   Host naf3
   	Hostname = nafhh-cms03.desy.de
   	Compression = yes
   	User = <user>
   	ForwardX11 = yes
  
   Host naf4
   	Hostname = nafhh-cms04.desy.de
   	Compression = yes
   	User = <user>
   	ForwardX11 = yes
  
   Host naf5
   	Hostname = nafhh-cms05.desy.de
   	Compression = yes
   	User = <user>
   	ForwardX11 = yes
  
   Host naf6
   	Hostname = nafhh-cms06.desy.de
   	Compression = yes
   	User = <user>
   	ForwardX11 = yes
  

• EKP@KIT

   Host ekplx*
   	Hostname = %h.physik.uni-karlsruhe.de
   	Compression = yes
   	User = <user>
   	ForwardX11 = yes
  
   Host ekpcms*
   	Hostname = %h.physik.uni-karlsruhe.de
   	Compression = yes
   	User = <user>
   	ForwardX11 = yes
  
   Host ekpams*
   	Hostname = %h.physik.uni-karlsruhe.de
   	Compression = yes
   	User = <user>
   	ForwardX11 = yes
  

• RWTH Aachen

   Host lx3b*
   	Hostname = %h.physik.rwth-aachen.de
   	Compression = yes
   	User = <user>
   	ForwardX11 = yes
   	ForwardX11Trusted yes
   	ProxyCommand = ssh -l <user> portal.physik.rwth-aachen.de "nc %h 22"
  
   Host rwthportal
   	Hostname = portal.physik.rwth-aachen.de
   	Compression = yes
   	User = <user>
   	ForwardX11 = yes
  
   Host rwthtunnel
   	Hostname = portal.physik.rwth-aachen.de
   	Compression = yes
   	User = <user>
   	ForwardX11 = yes
  

• LXPLUS@CERN

   Host lxplus	
   	Hostname = lxplus.cern.ch
   	Compression = yes
   	User = <user>
   	ForwardX11 = yes
  

Access to Remote Directories in File Browser

• Nautilus

Go to menu File and then Connect to server and type one of the following lines in the dialog that opens.

ssh://<user>@<remote machine>
ssh://<user>@<remote machine>:/<path>
ssh://<host alias from SSH config>

Then create a bookmark and you can easily edit your files with your favourite local and graphical editor.

• Finder

In order to mount a remote folder on your Mac, you need to install OSXFuse and sshfs at first. Both programmes can be downloaded here:

https://osxfuse.github.io/

Create a small script in your ~/bin/ directory on your Mac

vim ~/bin/mount_lx3b

And write there something similar to the example below, changing the pathes accordingly

#mount my shared_folder at portal.physik.rwth-aachen.de
sudo umount -f /Volumes/lx3b
sudo mkdir /Volumes/lx3b
#mount it
sudo sshfs -o volname=lx3b -o IdentityFile=/Users/greyxray/.ssh/id_rsa -o follow_symlinks -o allow_other,defer_permissions [email protected]:/home/home2/institut_3b/hlushchenko/ /Volumes/lx3b/

In order to mount the remote drive you now simply have to type:

sudo ~/bin/mount_remote_drive

Explanations

sshfs will find your ssh-keys only if you specify the full path to your homedirectory where your /.ssh folder is located. The usual "~" is not working here!

After that you need to chmod +x the file to make it executable.

• -o volname: specifies the name of the remote drive in your Finder.
• -o follow_symlinks: Enables you to use symlinks created on the remote machine.
• -o IdentityFile identifies you with your public rsa key.

Find your remote drive in the Finder and add it to the sidebar.

• Please note: When you reboot your Mac, you need to mount the folder again.
• Sometimes it is necessary to unmount the folder to be able to mount it again. For this you can add

sudo umount /Volumes/lx3b

in your script at the beginning. This will unmount and mount your drive each time you call the script.